To start, make the buttermilk: Add milk to a small mixing bowl and squeeze half a lemon in and stir. Set aside.
Wash radishes and their leafy tops. Thinly slice radishes and set aside. Add greens to the blender.
Peel and pit avocados (leaving ½ an avocado aside to shop for garnish) and add into the blender.
Pour in buttermilk, lime zest, garlic, olive oil and salt.
Blend together until smooth with no large chunks
Add in more milk if the mixture is too thick.
Refrigerate until chilled, at least 1 hour.
To serve, stir well and top with thinly sliced radishes, cubed avocados, a sprinkle of fresh chopped dill or cilantro, and a little drizzle of lime juice. Enjoy!